A diagnosis of irritable bowel syndrome depends largely on a complete medical history and physical exam.
Criteria for making a diagnosis
Because there are usually no physical signs to definitively diagnose IBS, diagnosis is often a process of ruling out other conditions. To help this process, researchers have developed two sets of diagnostic criteria for IBS and other functional gastrointestinal disorders — conditions in which the bowel appears normal but doesn't work (function) normally. Both criteria are based on symptoms after other conditions have been ruled out.
- Rome criteria. According to these criteria, you must have certain signs and symptoms before a doctor diagnoses irritable bowel syndrome. The most important are abdominal pain and discomfort lasting at least three days a month in the last three months, associated with two or more of following: improvement with defecation, altered frequency of stool or altered consistency of stool.
- Manning criteria. These criteria focus on pain relieved by defecation, having incomplete bowel movements, mucus in the stool and changes in stool consistency. The more symptoms present, the greater the likelihood of IBS.
Your doctor will likely assess how you fit these criteria, as well as whether you have any other signs or symptoms that might suggest another, more serious, condition. Some red flag signs and symptoms that suggest a need for additional testing include:
- New onset after age 50
- Weight loss
- Rectal bleeding
- Nausea or recurrent vomiting
- Abdominal pain, especially if it's not completely relieved by a bowel movement, or occurs at night
- Diarrhea that is persistent or awakens you from sleep
- Anemia related to low iron
If you fit the IBS criteria and don't have any red flag signs or symptoms, your doctor may suggest a course of treatment without doing additional testing. But if you don't respond to that treatment, you'll likely require more tests.
Your doctor may recommend several tests, including stool studies to check for infection or problems with your intestine's ability to take in the nutrients from food (malabsorption). You may undergo a number of tests to rule out other causes for your symptoms.
- Flexible sigmoidoscopy. This test examines the lower part of the colon (sigmoid) with a flexible, lighted tube (sigmoidoscope).
- Colonoscopy. In some cases, especially if you are age 50 or older or have other signs of a potentially more serious condition, your doctor may perform this diagnostic test in which a small, flexible tube is used to examine the entire length of the colon.
- X-ray (radiography). Sometimes doctors will use X-rays to obtain an image of your colon.
- Computerized tomography (CT) scan. CT scans produce cross-sectional X-ray images of internal organs. CT scans of your abdomen and pelvis may help your doctor rule out other causes of your symptoms, especially if you have abdominal pain.
- Lower GI series. In this test, doctors fill your large intestine with a liquid (barium) to make it easier to see any problems on the X-ray.
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- Lactose intolerance tests. Lactase is an enzyme you need to digest the sugar found in dairy products. If you don't produce this enzyme, you may have problems similar to those caused by irritable bowel syndrome, including abdominal pain, gas and diarrhea. To find out if this is the cause of your symptoms, your doctor may order a breath test or ask you to remove milk and milk products from your diet for several weeks.
- Breath tests. Your doctor may perform a breath test to look for a condition called bacterial overgrowth, in which bacteria from the colon grow up into the small intestine, leading to bloating, abdominal discomfort and diarrhea. This is more common among people who have had bowel surgery or who have diabetes or some other disease that slows down digestion.
- Blood tests. Celiac disease is sensitivity to wheat, barley and rye protein that may cause signs and symptoms like those of irritable bowel syndrome. Blood tests can help rule out this disorder. Children with IBS have a far greater risk of celiac disease than do children who don't have IBS. If your doctor suspects that you have celiac disease, he or she may perform an upper endoscopy to obtain a biopsy of your small intestine.
- Stool tests. If you have chronic diarrhea, doctors may want to examine your stool for bacteria or parasites.
- Irritable bowel syndrome. The National Digestive Diseases Information Clearinghouse. http://www.digestive.niddk.nih.gov/ddiseases/pubs/ibs/. Accessed April 23, 2014.
- Camilleri M. Peripheral mechanisms in irritable bowel syndrome. New England Journal of Medicine. 2012;367:1626.
- Ferri FF. Ferri's Clinical Advisor 2014: 5 Books in 1. Philadelphia, Pa.: Mosby Elsevier; 2014. https://www.clinicalkey.com. Accessed April 23, 2014.
- Wald A. Diagnosis of irritable bowel syndrome. http://www.uptodate.com/home. Accessed April 23, 2014.
- Wald A. Pathophysiology of irritable bowel syndrome. http://www.uptodate.com/home. Accessed April 23, 2014.
- Wald A. Treatment of irritable bowel syndrome. http://www.uptodate.com/home. Accessed April 23, 2014.
- Rome III diagnostic criteria for functional gastrointestinal disorders. Rome Foundation. http://www.romecriteria.org/criteria/. Accessed April 23, 2014.
- Cristofori F, et al. Increased prevalence of celiac disease among pediatric patients with irritable bowel syndrome: A 6-year prospective cohort study. Journal of the American Medical Association Pediatrics. In press. Accessed May 5, 2014.
- Brandt LJ, et al. An evidence-based systematic review on the management of irritable bowel syndrome. American Journal of Gastroenterology. 2009;104(suppl):1.
- AskMayoExpert. IBS. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2014.
- Lakhan SE, et al. Mindfulness-based therapies in the treatment of somatization disorders: A systematic review and meta-analysis. PLoS One. 2013;8:e71834.
- Muir JG, et al.The low FODMAP diet for treatment of irritable bowel syndrome and other gastrointestinal disorders. Gastroenterology & Hepatology. 2013;9:450.
- Vazquez-Roque MI, et al. A controlled trial of gluten-free diet in patients with irritable bowel syndrome-diarrhea: Effects on bowel frequency and intestinal function. Gastroenterology. 2013;144:903.
- Hungin APS, et al. Systematic review: Probiotics in the management of lower gastrointestinal symptoms in clinical practice — an evidence-based international guide. Alimentary Pharmacology and Therapeutics. 2013;38:864.
- Relaxation techniques for health: An introduction. National Center for Complementary and Alternative Medicine. http://nccam.nih.gov/health/stress/relaxation.htm. Accessed May 6, 2014.
- Herbs at a glance: Peppermint oil. National Center for Complementary and Alternative Medicine. http://nccam.nih.gov/health/peppermintoil. Accessed May 6, 2014.
- Manheimer E, et al. Acupuncture for treatment of irritable bowel syndrome. Cochrane Database of Systematic Reviews. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD005111.pub3/abstract. Accessed May 18, 2014.
- Lindfors P, et al. Effects of gut-directed hypnotherapy on IBS in different clinical settings — results from two randomized, controlled trials. American Journal of Gastroenterology. 2012;107:276.
- McKenzie YA, et al. British Dietetic Association evidence-based guidelines for the dietary management of irritable bowel syndrome in adults. Journal of Human Nutrition and Dietetics. 2012:25;260.
- Chao G, et al. Effectiveness of acupuncture to treat irritable bowel syndrome: A meta-analysis. World Journal of Gastroenterology. 2014;20:1871.
- Rey E, et al. Chronic constipation, irritable bowel syndrome with constipation and constipation with pain/discomfort: Similarities and differences. American Journal of Gastroenterology. In press. Accessed March 4, 2014.
- Camilleri M. Current and future pharmacological treatments for diarrhea-predominant irritable bowel syndrome. Expert Opinion on Pharmacotherapy. 2013;14:1151.
- Golden AK. Decision Support System. Mayo Clinic, Rochester, Minn. April 24, 2014.
- U.S. News best hospitals 2013-2014. U.S. News & World Report. http://health.usnews.com/best-hospitals/rankings/gastroenterology-and-gi-surgery. Accessed April 24, 2014.
- Picco MF (expert opinion). Mayo Clinic, Jacksonville, Fla. May 14, 2014.
- Ottillinger B, et al. STW 5 (Iberogast) — A safe and effective standard in the treatment of functional gastrointestinal disorders. Wiener Medizinische Wochenschrift. 2013;163:65.
- Dai C, et al. Probiotics and irritable bowel syndrome. World Journal of Gastroenterology. 2013;19:5973.
- Sisson G, et al. Randomised clinical trial: A liquid multi-strain probiotic vs. placebo in the irritable bowel syndrome — a 12 week double-blind study. Alimentary Pharmacology and Therapeutics. In press. Accessed May 18, 2014.
- Bauer BA (expert opinion). May Clinic, Rochester, Minn. May 16, 2014.
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